Storage stability of powdery seasonings is commonly improved by adding an excipient such as dextrin in an amount of 20 to 40% by weight of the powder to be obtained, and powdering the mixture. It is also known that deterioration in storage stability of a powdery seasoning prepared from a protein hydrolysate seasoning liquid, such as color thickening or caking during storage, is markedly improved by drastically decreasing the moisture content (for example, see Patent Literature 1), and that caking of a seasoning is prevented by adding fine water-insoluble dietary fiber (for example, see Patent Literature 2).
Also known is a method for producing a powdery seasoning, including forcibly filtering a soy sauce mash through a net to remove the unedible part derived from the raw material, followed by spray drying to make a dry powder (for example, see Patent Literature 3). Examples of known methods for producing a dry powder without removing the unedible part from the mash include a method of forming the mash into a film using a drum dryer and drying the film, or freeze drying the mash, followed by grinding. However, drying and grinding processes are individually necessary, and the whole amount of the dried seasoning must be ground. In addition, spray drying for making a powder concurrently with drying can cause clogging of the nozzles by the unedible part of the mash, so that spray drying cannot be used for this purpose.